Personal health data collection

ABSTRACT

The present invention provides a personal band held monitor comprising a signal acquisition device for acquiring signals which can be fixed to derive a measurement of a parameter related to the health of the user, the signal acquisition device being integrated with a personal hand-held computing device. The present invention also provides a signal acquisition device adapted to be integrated with a personal handheld computing device to produce a personal hand-held monitor as defined above.

FIELD OF THE INVENTION

The present invention relates to means for collecting personal healthdata. In particular, the invention relates a personal hand-held monitor(hereafter “a PHHM”) comprising a signal acquisition device foracquiring signals which can be used to derive one or more measurementsof parameters related to the health of a user, the signal acquisitiondevice being integrated with a personal hand-held computing device(hereafter “a PHHCD”). The PHHM uses the processor of the PHHCD tocontrol and analyse signals received from the signal acquisition device.The present invention also relates to a signal acquisition deviceadapted to be integrated with such a PHHCD. The present inventionfurther relates to systems for operating the PHHM and for handling thesignals acquired by the signal acquisition device. The present inventionfurther relates to a system for analysing, storing and transmittingsignals acquired by the PHHM via the Internet or for regulating the usesto which the data derived from those signals may be put.

BACKGROUND TO THE INVENTION

Cellphones (also known as mobile phones) are a part of everyday life. Inthe developed world, a large majority of adults have a cellphone. Theuse of cellphones is also becoming much more prevalent in developingcountries as it enables such countries to develop a communicationssystem without the need to install cabling. There have been variousproposals for using cellphones in healthcare. However, all of theseproposals have drawbacks.

Leslie, I et al., “Mobile Communications for medical care”, FinalReport, 21 Apr. 2011, reports on a major study by the University ofCambridge which identified the crucial contribution that cellphonenetworks will make to healthcare in developed, low income and emergingcountries by transferring “vital signs” and other data from localmeasurement devices to a central data collection and processingcomputer. It identified two separate industrial communities—those whomake cellphones and those who make medical devices.

Ladera, D et al., “Strategic Applications Agenda Version 3”, WorkingGroup on Leading Edge Applications, January 2010, www.cmobility.eu.org,is an e-mobility study which, considered the wide implications ofnetworked health care and stated: “Smart phones can collect measurementresults automatically and wirelessly from the measuring devices andseamlessly transfer the collected data to the doctor for furtheranalysis.”

“Healthcare unwired—new business-models delivering care anywhere”Pricewaterhouse Coopers' Health Research Institute, September 2010, is astudy which addresses the opportunity presented by wide access tocommunications but from the perspective of the medical profession andits impact on the medical business model.

In a review in 2009, the Apple Company identified a growing demand forusing its iPhone® as part of a communications chain from medical devicesto practitioners and others (seehttp://medicalconnectivity.com/2009/03/19/apple-targets-health-care-with-iphone-30-os/).

These reports are based on the use of existing medical devices andexisting cellphone technology and therefore require the presence of botha medical device industry and a cellphone industry. It is an object ofthe present invention to enable collection of health-related, datawithout the need for both these industries.

Tablet computers and portable personal computers are also becoming smallenough to be used as PHHCDs. Many such devices also includecommunications facilities such as WiFi or wireless telephoneconnectivity.

Personal, digital assistant devices (“PDAs”) are also now well-known,and include a processor for enabling a user to store and retrievepersonal data.

THE PRESENT INVENTION

According to a first aspect of the present invention, there is provideda personal hand-held monitor (hereafter “a PHHM”) comprising a signalacquisition device for acquiring signals which can be used to derive ameasurement of a parameter related to the health of the user, the signalacquisition device being integrated with a personal hand-held computingdevice (hereafter “a PHHCD”).

The PHHM of the present invention must be of such a size and weight thatit can readily be manipulated by a normal adult using one-hand to holdthe PHHM and the other hand to enter or retrieve data. Preferably, thePHHCD includes communications facilities, such as WiFi or wirelesstelephone connectivity.

By “integrated” is meant that the signal acquisition device and thePHHCD form a single physical unit wherein the signal acquisition deviceand the PHHCD remain in fixed relationship when either is moved. Allelectrical connections are provided within the PHHM.

The acquired signals may be analogue or digital and, if analogue, may beconverted to digital form for subsequent analysis by the processor ofthe PHHCD or for analysis by a remote data processing facility withwhich the PHHCD communicates using the Internet or other datacommunication means.

The PHHCD with which the signal acquisition device is integrated may bea cellphone, a tablet computer, a PDA or any other computing devicewhich can readily be manipulated by a normal adult using one hand tohold the device and the other hand to enter or retrieve data.

The present invention merges medical technology with PHHCD technology bycombining proven technological principles with novel supplementation tocreate a PHHM which allows its user to acquire measurements of personalhealth data solely by using the PHHM. If desired, the user maycommunicate those measurements to other parties.

The use of the PHHM of the invention is a significant improvement overthe use of the systems described in the studies referred to abovebecause the signal acquisition device is integrated with the PHHCD.Since the signal acquisition device must be small enough to beintegrated with the PHHCD without reducing its portability and is ableto make use of the infrastructure of the PHHCD, such as its display andbattery, it will be significantly less expensive than many of the knownmedical devices, which are too expensive for most users in low income oremerging countries and would deter even those in developed countries.The signal acquisition device exploit micro-electronic technology toreduce size and cost to a level at which the signal acquisition deviceintegrated with a PHHCD can become ubiquitous and personal to the user.

Preferably, the signal acquisition device is adapted to acquire signalswhile in contact with or very close to one or more parts of the user'sbody. In particular, the signal acquisition device may be adapted toacquire signals while at least a part of it is in contact with:

-   -   one or more of the user's digits/especially one or more fingers;    -   the skin near the carotid artery;    -   the user's chest, advantageously close to the heart; and/or    -   the inside of a user's ear or mouth.

The signal acquisition device includes one or more sensors for acquiringsignals which can be used to derive a measurement of a parameter whichis useful to relation to personal health. Preferably, the one or moresensors is(are) for acquiring signals related to blood pressure, pulsewave velocity, blood pressure waveform, temperature, blood oxygenpartial pressure, electrocardiogram, heart rate and/or respiratory rate.The signal acquisition device may include sensors for acquiring signalsfrom which measurements of more than one of the above-mentionedparameters can be derived. The signal acquisition device preferablyincludes one or more sensor(s) for acquiring signals from whichmeasurements of blood pressure, using, for instance, one or more ofsphygmomanometry, photoplesthy smography and measurement of pulse wavevelocity, can be derived.

The PHHM of the present invention may include one or more of thefollowing sensors and means. Particularly preferred combinations ofthese sensors and means are referred to below.

The signal acquisition device may include a temperature sensor foracquiring signals from which a measurement of local body temperature(i.e. the temperature near the location the sensor is applied to thebody) can be derived by the processor of the PHHCD. Advantageously, thesignal acquisition device also includes a sensor for acquiring signalsfrom which a measurement of ambient temperature can be derived by theprocessor. This may be the same sensor as is used in connection withmeasuring local temperature or may be a separate sensor. Preferably, theprocessor is adapted to derive the user's core body temperature from thesignals acquired by the temperature sensor.

As is well known, the temperature of a surface may be estimated bymeasuring the thermal radiation that it emits. For typical bodytemperatures, the radiation is concentrated at far infra-redwavelengths. It may be detected by a bolometer, in which a target isheated by the incident radiation and its temperature measured, eitherdirectly by detecting the change in its resistance or indirectly using athermocouple, thermistor or other similar device. The field of view maybe defined by a lens or window. The temperature sensor may be adapted toreceive radiation from the inside of the ear or the temporal artery onthe forehead as in existing medical devices using this technique.

The temperature sensor is preferably positioned so as to be able tosense the temperature of the user's ear, whether or not the user ismaking a telephone call. Alternatively, the temperature sensor may bepositioned so that it is able to make measurements of the surfacetemperature of the body part on which any other measurement made by thePHHM, such as a measurement of blood pressure, is to be made.

Alternatively, the temperature sensor may be located such that the usermay orientate its direction by manipulating the PHHM such that it isable to sense the temperature of the body part or other item chosen, forexample an item of the user's clothing. The processor of the PHHM may inthis case be adapted to derive a signal indicative of ambienttemperature and/or to provide instructions to the user to orient thePHHM so that signals indicative of body temperature and ambienttemperature are obtained.

Alternatively, the temperature sensor may be located on an arm which canbe brought into contact with one of the user's fingers or inserted intothe user's ear or mouth. The arm may be fixed in position on the signalacquisition device or may be movable between an extended and a retractedposition so that the arm can be retracted when not in use. The arm maybe pivotable or slideable between its extended and retracted positions.

The signal acquisition device may include more than one temperaturesensor for sensing temperature at different locations.

The temperature sensor may be used for measurement of the temperature ofother items, for example for food, domestic heating systems or wine.

Electrical Sensor

The heart is triggered by electrical signals that can be detected on theskin, which is the basis of the electrocardiogram (ECG). A simpleversion of this can detect the time at which the electrical signal thatinitiates a heartbeat occurs by measuring the potential differencebetween two separated parts of the body. With appropriate electronicprocessing, the time of occurrence of each initiation signal can bemeasured to within a few milliseconds.

The signal acquisition device may include an electrical sensorcomprising two electrodes which are electrically isolated from eachother but which can be contacted by two different parts of a user'sbody. Preferably, the two electrodes can be contacted by one finger fromeach hand of the user. Preferably, one of the electrodes of theelectrical sensor is associated with the button, pad or strap of theblood flow occlusion means (see below). The other electrode will belocated on a separate part of the PHHM. That other electrode may beassociated with a lever, if present, which is used for manual inflationof a pad (see below). Preferably the pad is constructed with a surfacethat gives a good electrical connection, such as an array ofmicro-pyramids.

Preferably, the signal which is acquired by the electrical sensor is ameasure of the potential difference between the two electrodes, which isrelated to the potential difference between the two different bodyparts. Preferably, the processor of the PHHCD is adapted to amplify thesignals from the electrical sensor and, if desired, to filter thesignals before, during or after amplification. An amplified and filteredsignal produced by the processor will generally have the form shown inFIG. 1 in the attached drawings where the x axis represents time and they axis represents potential difference. The arrows in FIG. 1 indicatethe time at which the electrical signal stimulates the heart to initiatesystole.

Blood Flow Occlusion Means

The signal acquisition device may comprise a blood flow occlusion meansfor restricting or completely blocking the flow of blood through a partof a user's body and a pressure sensor for determining the pressureapplied by or to the blood flow occlusion means. The conventional bloodflow occlusion means is an inflatable cuff that surrounds the. bodypart.

The signal acquisition device preferably includes one of the blood flowocclusion means that are described below; a button; a fluid-filled pad;and a strap. Any of these can be used by pressing it against a bodypart, such as a toe or finger, preferably a finger, where arterial bloodflow through the body part is affected by pressure exerted on only oneside of the body part, or vice versa.

The degree of occlusion may be detected by an oscillometric method or byanalysis of the signals from a blood photosensor described below.

Button

The blood flow occlusion means may comprise a button that is pressedagainst the body part. Preferably, the button is a region of a plate,which region may move independently from the remainder of the plate andis connected to a force sensor. The force sensor is adapted to measurethe force applied to the button but minimise the distance the button maymove. Typically, the plate is of 10 mm by 20 mm with a circular buttonof typically 5 mm diameter or a non-circular button of similar area.Preferably, the distance the button moves when subject to the force ofthe body part is no more than 0.1 mm.

Pressing the button against the body part creates a pressure within thebody part. The body part in contact with the button pushes against thebutton with a force approximately equal to the pressure within the bodypart multiplied by the area of the button. By measuring the force, thePHHM can make an accurate estimate of the pressure within the body part.

The signal acquisition device may include a plurality of buttons, eachof which is connected to a separate force sensor.

Fluid-Filled Pad

The blood flow occlusion means may comprise a fluid-filled pad againstwhich one side of a part of the user's body, in particular a digit,preferably a finger, can be pressed to occlude the flow of blood throughthat part of the body, and a pressure sensor for providing a signalindicative of the pressure in the pad. Preferably, the pad is located ina notch in the PHHM. In use, pressure may be applied to the pad eitherby pressing the body part onto the pad or by pressing the pad onto thebody part.

If the pad is filled with air, it may be necessary to provide a means toprevent excess pressure occurring in the pad. This may arise, forexample, if the device is left in a hot place and the heat causes thepressure to rise excessively. The excess pressure prevention meanspreferably includes a valve that opens to release gas from the pad tothe atmosphere at a predetermined pressure, which is the maximumpermitted pressure of the pad (typically around 300 mm Hg) and a pumpfor replacing the gas which has been released. The pump may comprise apiston and cylinder or if may comprise a diaphragm and chamber, and thepiston or diaphragm may be operable by an action of the user or byelectrical power. Preferably, the PHHM has a hinged or sliding coverover the signal acquisition device arranged such that, on opening thecover to allow the device to be used, the cover presses on the piston ordiaphragm to create sufficient pressure to re-inflate the pad.Preferably, the pump has two valves: a one-way valve that allows gas toenter the pad; and a valve for opening to release gas from the pump tothe atmosphere at a predetermined pressure, which is the minimum workingpressure of the pad (typically around 50 mm Hg).

It is advantageous that the volume of gas present in the pad isminimised, to maximise the sensitivity of the detection of changes inpressure. If a one-way valve is used, it should preferably be locatedclose to the pad and to the pressure sensor.

A further benefit of incorporating this prevention means is that thedevice continues to operate even if a slow leak develops. This willincrease the reliability of the device.

Strap

In a further alternative, the blood flow occlusion means may comprise astrap against which one side of a part of the user's body, in particulara digit, preferably a finger, can be pressed to occlude the flow ofblood through that part of the body, and a force sensor for providing asignal indicative of the pressure exerted on the strap.

Preferably, the strap is located in a notch in the PHHM. In use,pressure may be applied to the strap either by pressing the body partonto the strap or by pressing the strap onto the body part.

The strap may be inextensible or extensible.

Where the strap is inextensible, it may be fixedly mounted at each endacross a notch in the PHHM. In this arrangement, the pressure sensor isadapted to measure the force applied to the strap's mountings.

Alternatively, an inextensible strap may be mounted on an axle at oneside of a notch and fixedly mounted at the other side of the notch. Inthis arrangement, the pressure exerted on the strap may be measured bymeasuring the extent to which the strap has rolled around the axle. Theunrolling may be resisted by a torque spring on the axle or a linearspring.

In a further alternative, an inextensible strap may be mounted at eachof its ends on an axle and the axles are located at each end of a notchin the PHHM. In this arrangement, the pressure exerted on the strap maybe measured by measuring the extent to which the strap has rolled aroundeach axle or by measuring a physical property of the strap, such as itselectrical resistance.

Where the strap is extensible, it may be fixedly mounted at each endacross a notch in the PHHM. In this arrangement, the pressure sensor maybe adapted to measure the increase in length of the strap or the tensionin the strap or to measure a physical property of the strap, such as itselectrical resistance, to provide the signal related to the pressureapplied to the strap.

Where a strap is used, it is preferred that the PHHM includes means forproviding a signal indicative of the diameter of the body part whichcomes into contact with the strap so that the pressure measurement canbe made more accurate. The means may be a keypad or a touchscreen,advantageously the normal keypad or touchscreen of the PHHCD, by which auser may enter the diameter as measured by the user, for instance usingany convenient means, such as a tape measure or a series of graduatedcut-outs provided on a separate gauge or provided on the PHHM.

However, it is preferred that the means is associated with the strapitself and provides the signal without user input. For instance, thestrap may include one or more optical fibres embedded therein, a lightsource at one end of the optical fibre(s) for injecting light into theoptical fibre(s) and a light detector at the other end of opticalfibre(s) for detecting the light reaching the detector and a means fordetermining the attenuation of the light as it passes through theoptical fibre(s), the degree of attenuation being related to thecurvature of the strap, which in turn is related to the diameter.Alternatively, the strap may comprise two layers and the signalacquisition device includes means for measuring the length of eachlayer, the relative lengths of the two layers being related to thediameter. In a further alternative, the signal acquisition device mayinclude means, such as a proximity detector, for providing a signalindicative of the distance between the bottom of the notch and theclosest point of the strap to the bottom of the notch and the processoris adapted to calculate the diameter of the body part based on thesignal and the length of the strap.

Blood Photosensor for Photoplethysmograph (PPG)

Pulse oximeters using PPG have been on the market since the 1980s. Theyare used to estimate the degree of oxygenation in arterial blood. Redand infra-red light is transmitted towards a body part. The infra-redlight is more strongly absorbed by oxygenated blood than bynon-oxygenated blood; red light is more strongly absorbed bynon-oxygenated blood than by oxygenated blood. The change in theinfra-red absorption during systole is a measure of the amount ofoxygenated blood. The level of red light absorption between systoles isa measure of the total amount of blood being illuminated and is used forcalibration.

Preferably, the signal acquisition device includes a PPG sensor. Thisuses one or more photosensors. The photosensor(s) may be arranged fortransmission or scattering measurement. In transmission mode, thephotosensor comprises one or more photo-emitters arranged to transmitlight through the body part, and one or more photo-detectors arranged todetect light transmitted from the photo-emitter(s) through that part. Inscattering mode, the photosensor comprises one or more photo-emittersarranged to transmit light towards the body part and one or morephoto-detectors arranged to detect light from the photo-emitter(s)scattered by the body part. Preferably, in scattering mode, thepboto-detector(s) is(are) arranged in close proximity to thephoto-emitter(s).

Preferably, in either case, the photosensor(s) is/are adapted to emitand detect light at two or more wavelengths. There may be a single,multiplexed photo-emitter adapted to emit light of two selected,different wavelengths or at least two photo-emitters, each of which isadapted to emit light of a selected, different wavelength. For eitheralternative of the photo-emitter(s), in one alternative, there is onemultiplexed photo-detector which can detect light at the selectedwavelengths. In another alternative, there are two or morephoto-detectors, each of which is adapted to detect light of a selected,different wavelength.

Preferably, one of the wavelengths is chosen so that the light isabsorbed more strongly by oxygenated blood than by deoxygenated blood. Asuitable wavelength is 940 nm. Another wavelength is chosen so that, thelight is absorbed more strongly by deoxygenated blood than by oxygenatedblood. A suitable wavelength is 660 nm.

Preferably, the signal acquisition device is adapted to acquire a signalfrom the photo-detector(s) when no light is emitted from thepboto-emitter(s). This allows a further calibration of the signalsobtained at the first and, if used, second wavelength(s).

FIG. 2 in the attached drawings shows schematically the variation inoxygenated blood signal (top line), deoxygenated blood signal (middleline) and ambient light signal (bottom line).

The blood photosensor may be further adapted to measure theconcentration of analytes in the blood such as glucose, alcohol,haemoglobin, creatinine, cholesterol and stimulants or other drugs,including illegal or otherwise forbidden substances. These are difficultto measure if the absorption spectrum of the analyte is similar to thatof other materials in the blood. The signal acquisition device may bedesigned to use one or more of the techniques described below toincrease the sensitivity and selectivity of absorption spectroscopy.

The first technique is to use differential absorption. A beam of lightis transmitted towards a body part and the transmitted or scatteredlight is split between two sensing cells. One (the reference cell)contains a mixture of the chemical species typically present insufficient quantities in blood, excluding the analyte of interest. Inpractice this might only contain water. The other (the sample cell)contains the same mixture and the analyte. Alternatively, the referencecell maybe omitted and the sample cell filled solely with the analyse.Alternatively, if the analyte can be gaseous under ambient conditions,the beam of light may pass through a single sample ceil containing theanalyte in gaseous, form and the pressure in that cell is modulated.

The intensity of the beam of light may be measured under severalconditions: after passing through the reference cell and separatelyafter passing through the sample cell, in each case without the bodypart present, and similarly after passing through each cell with thebody part present. Alternatively, the intensity of the beam of light maybe measured both when it has passed through the cell and when it hasnot, again with the body part present and not. In another alternative,the intensity may be measured as a function of the pressure in the cell,with and without the body part present.

The intensity of the beam of light may be modulated, for example byswitching, to allow the measurement system to compensate for ambientlight. The beam of light has a broad optical spectrum chosen to maximisethe discrimination between the analyte and other chemical speciespresent whilst also allowing low cost technology to be employed. Forexample, if the analyte is glucose, this might be in the near IR region.

In each of these cases, the difference between the intensity when thebeam of light has passed through the reference cell and through thesample cell is a measure of the amount of absorption by the analytewithin the body part. In order further to improve the selectivity to theconcentration of the analyte in blood, the PPG signal may be used toidentify the time at which the artery dilates due to systole. The changein absorption at this point is a consequence solely of the additionalamount of blood in the body part. The volume of that additional blood isalso estimated from the PPG signal.

Acoustic Sensor

The PHHM may include an acoustic sensor for acquiring signals related tothe sounds produced by the heartbeat. The acoustic sensor may be aseparate microphone, geophone or vibration sensor or may be themicrophone provided in a standard cellphone or tablet computer forspeech reception or it may be the force or pressure sensor used tomeasure the pressure in the body part during arterial occlusion.Preferably the processor of the PHHM is adapted to process the signalsacquired by the acoustic sensor to determine the time at which the heartbeats.

FIG. 3 in the attached drawings shows a typical waveform of the“lub-dub” beat of the heart which would be acquired by the acousticsensor. Two successive pulses are shown. The signal consists of an audiosignal within an envelope of amplitude.

Movement Sensor

The PHHM may also include a movement sensor which is adapted to detectthe location of the part of the user's body on which the signalacquisition device is located. Preferably, the processor of the PHHM isadapted to correlate the signal from the movement sensor with the signalfrom a pressure sensor to enable calibration of blood pressuremeasurement. Preferably, the processor of the PHHM is adapted to issueinstructions audibly or visibly to the user to move the body part sothat such calibration can take place. The movement sensor may be anexisting component of the PHHCD. It may detect inertial forces due tothe acceleration of the PHHCD or pressure changes with altitude.

Ultrasonic Sensor

The signal acquisition device may include an ultrasonic sensor forforming an image of the cross-section of the artery and/or to useDoppler interferometry to estimate the flow velocity of the blood withinthe artery. Said ultrasonic sensor may consist of a set of individualelements that form an array.

Personal Data Entry Means

Preferably, the PHHM includes a personal data entry means and is adaptedto store other personal data. The personal data entry means ispreferably a keypad or touchscreen, advantageously the normal keypad ortouchscreen of the PHHCD. The data which can be entered by these meansmay include but are not restricted to: height, weight, waistcircumference, finger diameter and age.

Further Sensors and Means

The PHHM may further include means for applying electrical signals tothe user's body and for detecting the signals produced in response tothose signals, for instance to measure body properties such as body massindex.

The PHHM may include a sensor adapted to acquire signals from which theidentity of the user can be derived, such as for taking a fingerprint ofthe user. This makes it possible to ensure that the derived measurementsrelating to the user's health can be associated directly to the user.Such an identity sensor may be associated with the pad of a blood flowocclusion means or may be associated with an electrode of an electricalsensor. It is possible to locate the identity sensor in such a way thatit is almost impossible for the measured medical indicators to be of anyperson other than the identified user.

DATA ANALYSIS

The sensors and means described above may be used in variouscombinations to allow for the acquisition of various health-relateddata. The PHHM may include one or more of the temperature sensor,electrical sensor, blood flow occlusion means, blood photosensor forPPG, acoustic sensor, movement sensor, ultrasonic sensor and preferablyincludes at least the first four of these. Preferred combinations ofsensors and means are set forth in the Table below, together withindications of the health-related data that may be derived using thesecombinations. However, it will be clear to the person skilled in the artthat other combinations can be used to provide further health-relateddata and the present invention is not to be limited to the combinationsset forth in the Table below.

Health- related Measurement Relevant parameter technique sensors NotesBody Bolometry Temperature Bolometry is a mature technique. ThePHHMpreferably uses temperature sensor feedback to guide the user to obtainthe highest value (for example by moving around over the ear) and amodel to extrapolate the changes as measured to estimate an asymptoticvalue and to correct for ambient. Pulse rate Timing of Electrical Thesignal from the electrical sensor will be the most reliable and pulsessensor precisely timed. The signals from the two sensors will also bePulse Timing of Pressure analysed to provide confirmation of the dataand to improve arrhythmia pulses sensor accuracy. The analysis will,like that for blood pressure, seek the Blood most likely value in thelight of all of the available evidence. photosensor Blood PulseElectrical Pulse Wave Velocity (PWV) is a direct measure The actualpressure Wave sensor of blood pressure. The electrical sensor may bloodpressure (systolic Transition Blood be used to detect the time ofinitiation of may be and Time photosensor the pulse. The acoustic sensormay be used estimated by diastolic) (PWTT) Acoustic when the user firstcalibrates the device to combining the sensor measure the time betweenelectrical signal five separate Personal and start of systole. The PPGsensor may be measurements data used to detect the time at which thepulse (or as many as reaches the finger. The personal data may be areavailable). used to estimate the path length from heart The combinationto PPG sensor. might not just Pulse Blood The magnitude of the PPGsignal is a measure be a simple volume photosensor of the change inarterial volume, which is average; the related to blood pressure.processing may Sphygmoma- Pressure Pressure The applied pressure ismeasured Both seek to find the nometry fluctuations sensor by thepressure in the pad or the techniques most likely (occlusion) force onthe strap or button. The may use value in the blood flow rate can bedetected feedback light of all by small changes in the pressure to guideavailable caused by changes in volume of the user information, theartery. to push using a Optical Pressure The pulse volume depends on theharder or technique such absorption sensor external pressure, unaffectedif softer to as a Bayesian Blood it is less than diastolic and map theestimator to photosensor falling to zero at systolic. pressure takeaccount of space. all data Timing of As pulse There is a correlationbetween pulse rate and including pulses rate blood pressure. Personaldata, including variations records or previous measurements, will add tobetween pulses. its relevance. Blood PPG Blood Standard PPG technique,combining measurements of infra-red oxygen photosensor and visibleabsorption where the pulse reaches the finger. Pulse PWTT As above, inblood pressure measurement Wave Velocity Respiration Effect on Blood Therespiration cycle is manifested in The actual cycle blood photosensorchanges to the interval between pulses, respiration cycle pressure themean level of blood pressure and the may be obtained by and pulsemagnitude of the PPG signal combining the four Electrical Therespiration cycle is manifested in separate estimates sensor changes tothe interval between pulses. (or as many as are available). Blood flowPerturbation Blood The user may be instructed to hold his/her breath.The level of rate of photosensor blood oxygen falls after the lessoxygenated blood has reached respiratory the measurement point, andrises again after a breath is taken cycle and the more oxygenated bloodarrives

The Table does not refer to the analysis of the data derived from thepossible extension of the optical sensor to measure the concentration ofan analyte in the blood.

Algorithms relating the combination of signals from any or all of thesensors and means contained in the PHHM and from other sensors that maybe part of the PHHCD may be used to convert the acquired signals to therelevant health-related data or improve the accuracy of the deducedmedical indicators (“vital signs”), such as systolic and diastolic bloodpressure. Other medical indicators that are less well-known but whichare recognised by medical specialists, such as arterial wall stiffnessand pulse arrhythmia, may also be extracted. Any or all of these modelsmay be coded as software and can be loaded onto the PHHM or onto aremote computer for processing of the signals.

Preferably, the processor of the PHHM is adapted to provide audible orvisual instructions to the user to enable the user to use the PHHMoptimally. In this case, it is preferred that the processor is adaptedso that the instructions are interactive and based on signals receivedfrom the signal acquisition device, which can be used to determinewhether the signal acquisition device is in the best position or beingused correctly.

It is preferred that the processor is adapted to take multiplemeasurements and correlate all the measurements to provide a betterindication of the health data. One possible arrangement by which thedata from the sensors is analysed is described after the Table.

Body Temperature

The accuracy of the estimate of core temperature can be improved byadapting the processor of the PHHCD to provide audible or visualfeedback for instructing the user to move the PHHM so as to give themaximum temperature reading, for example when the PHHM is against theuser's ear and is moved to ensure that the sensor is directed to thewarmest place.

Preferably, the temperature sensor is positioned in the PHHM so that thePHHM is able to cover the body part whose temperature is being measured,such as the ear. In this case, in use, the temperature may rise towardscore temperature because drafts are excluded by the presence of thePHHM. The temperature sensor may be collocated or combined with aloudspeaker or other device used to reproduce sound in the PHHCD.

Preferably, the processor is adapted to record the measured temperatureover a period of several seconds and to use a mathematical model toextrapolate to an expected equilibrium temperature.

The processor of the PHHM may be adapted to analyse the signals from thetemperature sensor to provide an estimate of the core body temperatureof the user. the processor may be further adapted to carry out analysisto identify trends in core temperature and other derived information ofdiagnostic value.

Pulse Rate

the time of each pulse may be determined from the electrical signal,which indicates initiation of the systole, and also from the time ofarrival of the systolic pulse at the body part against which the deviceis pressed, indicated by the pressure on the pressure or force sensor inthe occlusion means and by the absorption peak detected by the opticalsensor and/or by the acoustic sensor, if present.

The average pulse rate most compatible with all of the data from each ofthose sensors is found by means of an optimising mathematical algorithmwhich the processor of the PHHCD is adapted to operate. This may be asimple least-squares difference calculation with weighting or may use aBayesian estimator or other optimising technique to find the most likelyestimate.

Pulse Arrhythmia

Arrhythmia is a term used to refer to the variation of the intervalbetween pulses. The patterns of such variations are a valuablediagnostic tool.

The variations may be obtained from the same data as is used to find theaverage pulse rate, again optionally using an optimising mathematicalalgorithm.

Blood Pressure

Blood pressure may be estimated by combining the data from fourdifferent types of evidence: pulse wave velocity, pulse volume,sphygmomanometry and pulse rate. Sphygmomanometry is itself derived fromtwo different measurements, from the high frequency signals from thepressure sensor and from the blood photosensor(s). External data, suchas height, weight, age and sex of the user, may also be exploited. Thereare thus five separate measurements and several pieces of data that maybe combined using an optimising mathematical algorithm such as aBayesian estimator to obtain the most reliable estimate of bloodpressure.

The resulting values are the systolic and diastolic blood pressure atthe location of the body part at which the measurement was made. Otherdiagnostic information may be extracted from the signals by means offurther mathematical models. For example, the analysis may calculate theblood pressure at another point on the body, such as the upper arm so asto allow direct comparison with the measurements by a conventionalcuff-based sphygmomanometer. It may also calculate pressure at the aortaand also arterial stiffness.

Optionally the PHHM may include a further temperature sensor to detectthe artery to be tested.

Each of the measurements of blood pressure is described below.

Pulse Wave Velocity

Pulse wave velocity (PWV) may be derived from pulse wave transition time(PWTT).

The use of PWV to estimate blood pressure (BP) is described in detail byPadilla et al. (Padilla, J et al., “Pulse Wave Velocity and digitalvolume pulse as indirect estimators of blood pressure; pilot study onhealthy volunteers” Cardiovasc. Eng. (2009) 9:104-112), which in turnreferences earlier work on a similar subject from 1995 and its specificuse for estimating of BP in 2000. The technique is described in U.S.Pat. No. 5,865,755 dated Feb. 2, 1999. It relies on the observation thatthe speed at which a blood pulse travels along the arteries is afunction of the arterial blood pressure.

Preferably, the processor of the PHHM is adapted to derive an estimateof PWV from the signals obtained from the electrical sensor and the PPGsensor. The processor is adapted to process the signal from theelectrical sensor to provide an indication of the time at which systole(the heart beat) is initiated and to process the signal from thephotosensor to determine time of occurrence of the peak in theoxygenated signal, which indicates the time at which the pulse reachesthe measurement point. The interval between these is a measure of thetime taken from the pulse to travel from the heart to the measurementpoint (the PWTT). The processor is adapted to determine the BP inrelation to this interval, which is typically 300 ms for measurements atthe end of the wrist or hand.

Preferably, the processor is adapted to make use of two further piecesof information to estimate PWV: the time delay between the electricalinitiation signal and the initiation of systole by the heart, and thelength of the path between the heart and the measurement point.

Preferably, the processor is adapted to analyse the acoustic signal toextract the envelope (analogous to detection in radio signals) and touse a threshold set automatically to identify the point that indicatesthe initiation of systole. In practice, this could be at a definedfraction of the change from background and peak, as shown in FIG. 4 ofthe attached drawings, where the vertical arrows indicate the time atwhich the heart responds to a physiological electrical initiation signaland initiates systole. This is typically a few tens of millisecondsafter the electrical initiation signal. Alternatively, the processor isadapted to match a curve to the waveform to make a more robust estimate.

Alternatively, the time delay may be estimated by measuring the PWTT totwo different parts of the body, such as the carotid artery and thefinger. The time delay can then be found from knowledge of the typicalratio of the path lengths from the heart to the two different parts ofthe body.

Preferably, the PHHM is adapted to store the time delay in non-volatilememory. It may be stored automatically when measured or entered intomemory by user input using a keypad or touchscreen, advantageously thenormal keypad or touchscreen of the PHHCD.

Preferably, the PHHM is adapted to store in non-volatile memory a valuerelated to the length of the path between the heart and the measuringpoint. It may be entered into memory by user input using a keypad ortouchscreen. The value entered may be an exact measure of the length ormay be a value which is approximately proportional to the actual length,such as the user's height.

Pulse Volume

Pulse volume may be derived from the blood photosensor (PPG). The use ofPPG for estimating BP was reported by X. F. Teng and Y. T. Zhang at theIEEE EMBS, Cancun, Mexico, Sep. 17-21, 2003. The basic technique was thesubject of U.S. Pat. No. 5,140,990, dated Aug. 25, 1992. The change ofthe infra-red absorption during systole is a measure of the change involume of the artery being illuminated, which is related to the pressurewithin the artery.

Further data may be derived from analysis of the shape of the absorptionpeak during systole, such as analysis of the total area under the peak.

Preferably, for the signal for oxgenated blood, the processor of thePHHM is adapted to derive properties of the blood flow such as therelative amplitude and timing of the direct and reflected pressure wavefrom the shape of the curve such as from the area under the peak, itswidth at half-height and the height and width of the shoulder.Optionally, the processor of the PHHM may be adapted to calculate ratiosof these to reduce the effect of variations in illumination and locationrelative to the body part. These ratios may be used to characterise theproperties of the blood flow.

The processor of the PHHM is preferably adapted to analyse the signalsfrom the PPG sensor to provide a direct estimate of systolic anddiastolic blood pressure at the point of measurement.

Sphygmomanometry (Arterial Occlusion)

Sphygmomanometry is a mature technique for measuring BP which has beenin use for more than 100 years. Variable external pressure is appliedwith a cuff around the body part within which an artery runs. Thepressure reduces the cross-section of the artery and restricts the flowof blood during systole.

Sphygmomanometry is conventionally conducted with a cuff that surroundsthe body part and is inflated to a pressure at which all blood flow isstopped; the pressure is then slowly released. Systolic BP is measuredby finding the smallest pressure that completely occludes the flow.Diastolic BP is measured by finding the largest pressure that does notcause any occlusion. The flow traditionally is detected by a skilledpractitioner using a stethoscope to hear the sounds of the blow flowing(Korotkoff sounds).

Automatic sphygmomanometers detect the flow either by detectingfluctuations in pressure in the cuff caused by the flow (osillometricmethod, see, for example, the Freescale Application Note AN1571,“Digital Blood Pressure Meter”) or by optically sensing small movementsof the skin. The magnitude of those fluctuations is an indicator of thedegree of occlusion. More recently, PPG has been used by combiningsphygmomanometry with the measurement of pulse volume (see Reisner etal., “Utility of the Photoplethysmogram in Circulatory Monitoring”Anesthesiology 2008; 108:950-8).

The signal acquisition device may use any one of the three means ofocclusion described above: a fluid-filled pad, a strap or a button. Ituses both the pressure fluctuations and the measurement of pulse volumeto determine the systolic and diastolic pressures.

Unlike conventional sphygmomanometry, flow may be detected at a range ofpressures in any order and the data fitted to a known mathematicalequation. It is preferred that the processor is adapted to issue audibleor visual instructions to the user to vary the force applied to the bodypart to cover a wide enough range of pressures to give a good fit tothat mathematical equation. For instance, if the user has not pressedhard enough against the button, strap or pad referred to above toocclude completely a blood vessel during a systole, the device may beprogrammed to issue an instruction to the user to press harder on theocclusion means (or vice versa) so that the required data can beacquired.

This capability allows the pressure applied to the occlusion means to beapparently random. In carrying out blood pressure monitoring, the usermay vary the pressure applied to the button, pad or strap referred toabove in a random manner. However, the data from the blood flow sensorcan be correlated with the signal from the pressure sensor of thebutton, pat or strap to fit the measured data to a known theoreticalrelationship between flow rate and pressure (see, for example, the modelshown on page 954 of Reisner (“Utility of the Photoplethysmogram inCirculatory Monitoring” Anesthesiology 2008; 108:950-8).

Pulse Rate

Pulse rate may be measured separately and can be used as an indicator ofblood pressure. Al Jaafreh (“New model to estimate mean blood pressureby heart rate with stroke volume changing influence”, Proc 28th IEEEEMBS Annual Intnl Conf 2006) concludes that: “The relationship betweenheart rat (HR) and mean blood pressure (MBP) is nonlinear”. The paperthen shows how allowance for stroke volume can compensate for some ofthat non-linearity. Stroke volume is estimated separately (see below)and personal data may also be used.

Blood Oxygen

The blood photosensor can use PPG to estimate blood oxygen levels. Atleast four variables may be derived from the measured absorption at twowavelengths. These are the amplitude of the detected signal at eachwavelength at a systole and between systoles. The arrow in FIG. 2 showsone of the values that may be derived from these, the height of the peakcorresponding to the change in oxygenated blood signal at systole. It isestablished that these four values may be analysed to estimate theoxygenation of the blood (see for example Azmal et al., “ContinuousMeasurement of Oxygen Saturation Level using Photoplethysmographysignal”, Intl, Conf. on Biomedical and Pharmaceutical Engineering 2006,504-7).

Pulse Wave Velocity

the pulse wave transition time may be measured as set out above andconverted into an estimate of Pulse Wave Velocity. This information isof direct diagnostic value to a skilled medical practitioner, especiallyif considered with all the other data obtainable from the signalacquisition device of the present invention.

Respiration Cycle

The state of the respiration cycle may be detected from several of thedata sets measurable by the present invention:

-   -   pulse rate (measured by electrical sensor and blood photosensor,        see above);    -   mean blood pressure (see above); and    -   amplitude of the systolic pulse (measured by PPG, see above).

The results of all of these measurements may be combined using anoptimising mathematical algorithm such as a Bayesian estimator to obtainthe most reliable description of the amplitude and phase of therespiratory cycle.

Blood Flow Rate/Heart Stroke Volume

The volume pumped by the heart on each pulse is conventionally measuredusing an ultrasound scan. The cross-sectional area of the aorta isestimated from the image and the flow rate from the Doppler shift. Thisis a mature and inexpensive technique but is only available at thedoctor's office.

Before ultrasound was readily available, a convenient and almostnon-invasive technique was to estimate the time taken for blood tocirculate around the body. This is related to the pulse rate and thevolume pumped on each pulse. The technique used a strong-tasting butharmless chemical that was injected into a vein in the arm and the timemeasured before it reached the patient's tongue and could be tasted.

The present invention allows a similar measurement to be made bypeturbing the respiratory cycle. The PHHCD may be adapted to instructthe user to hold his/her breath. The level of oxygen in the lungs startsto fall and the oxygenation of the blood in the lungs falls with it.Once this blood reaches the body point at which measurements are beingmade, the blood oxygen level will be seen to fall. The time interval,when combined with assumed or entered data as to the path length, is ameasure of flow velocity. The PHHCD then instructs the user to startbreathing again and the time taken for the blood oxygen level to startto rise again may also be measured.

REMOTE DATA PROCESSING

The PHHM is capable of making and displaying measurements of any or anycombination or all of the “vital signs” listed above without anyexternal data processing. Additional features are improved accuracy maybe provided by external data processing, using the communicationscapability of the PHHCD to connect to the Internet, a cellular telephonenetwork or other communications means.

Preferably, each PHHM according to the invention has a unique,unalterable, electronically-readably identifier. This may be providedduring manufacture or testing. Furthermore, each PHHM preferablyincludes circuitry to encrypt the measured data in a manner that isunique to that device.

In one embodiment of the present invention, the PHHCD reads the uniqueidentifier when the PHHM is first used and transmits the identifier to aremote secure data service (RSDS) by means of the Internet. The RSDSdownloads to the PHHCD the necessary software, calibration data anddecryption key to extract the data from the PHHM. This is a morereliable way of ensuring the proper calibration of the signalacquisition device and minimises the time required for installation andfinal test of the PHHM into PHHCD. The PHHCD is preferably furtherprogrammed to communicate the measured data directly to the user, forinstance via a visual display or audibly. Preferably, the communicationis via a visual display. If desired, the processor may be programmed sothat the display shows not only the measured parameter(s) but alsotrends in the measured parameter(s).

Optionally, the software may be time-limited, requiring the user torevalidate it with the RSDS after a fixed period of time. Optionally,the user may be required to pay a licence fee for some or all of thecapability to be enabled.

Alternatively, the decryption key and calibration data may be retainedby the RSDS. The PHHCD transmits the encrypted raw data from the PHHM tothe RSDS for analysis. The RSDS then returns the decrypted, calibrateddata fro further processing and display to the user.

The RSDS may carry out further processing of the measured data to obtaingreater accuracy or to derive further diagnostic or indicative data.These data may be retransmitted to the PHHCD for display to the user.

The PHHCD may also be programmed by the RSDS to transmit the acquiredsignals or the derived measurements to a remote location, for instance auser's, clinician's, health care provider's or insurance company'scomputer system where the acquired signals or measurements may beprocessed remotely, for instance to provide a more accurate analysis, orfor the results of the analysis to be interpreted either automaticallyor by a skilled doctor. If the processor is so programmed, it may alsobe programmed to receive the results of such analysis and display suchresults to the user, as described above.

The PHHCD may also be programmed by the RSDS to permit third partyapplications (commonly known as “apps”) access to the data from thePHHM. Such permission may be made subject to the payment of a licencefee or to the app having been endorsed by the relevant regulatoryauthorities.

The PHHCD may also be programmed to provide information related to thederived measurement(s), such a normal ranges or recommendations foraction.

The RSDS can offer a service to store many measurements from a PHHM andanalyse trends and other derived information for the user. This may belinked to an automatic alert service in the event of any significantchanges in the data. In addition, the signals or measurements can beanonymized and gathered form groups of or all PHHMs of the invention sothat they can be used for research purposes.

PHYSICAL CONSTRUCTION

A number of different sensors and means, as referred to above, can beincorporated into the PHHM. They can be incorporated individually or inany combination of two or more sensors. For instance, a combination of asensor for measuring the pressure applied by a pad, strap or button, orapplied to a pad, strap or button, a photosensor for measuring bloodflow in a body part to which the pressure is applied and an electricalsensor for measuring pulse rate is particularly useful for providingmore accurate data for determining blood pressure. Preferably, the PHHMintegrates one or more Application Specific Integrated Circuits (ASIC),one or more Micro-Engineered Measurement Systems (MEMS) and/orphoto-emitters and/or photo-detectors. They may be integrated asseparate silicon devices in a single package or, preferably, some or allof them may be incorporated on one or more silicon devices. Suchintegration will bring several benefits, included reduced cost, improvedreliability, reduced size and mass and reduced power consumption.

Preferably the PHHM exploits the other capabilities of PHHCD forcalibration and operation.

Four embodiments of the present invention will now be described by wayof example only with reference to the accompanying drawings, in which:

FIG. 1 shows a generalised amplified and filtered signal acquired by anelectrical sensor;

FIG. 2 shows schematically the variation in oxygenated blood signal (topline), deoxygenated blood signal (middle line) and ambient light signal(bottom line) acquired from a PPG sensor;

FIG. 3 shows a typical signal waveform of the “lub-dub” beat of a heartacquired by an acoustic sensor;

FIG. 4 shows the envelope derived from the acoustic signal of FIG. 3;

FIG. 5 is a schematic illustration of a first embodiment of the presentinvention;

FIG. 6 is a schematic illustration of a second embodiment of the presentinvention;

FIG. 7 is a schematic illustration of a third embodiment of the presentinvention;

FIG. 8 is a schematic illustration of a fourth embodiment of the presentinvention;

FIGS. 9, 10 and 11 each shows an arrangement for an optical sensor to beused in a PHHM of the present invention.

It should be clearly understood that the following description of thesethree embodiments is provided purely by way of illustration and that thescope of the invention is not limited to this description; rather thescope of the invention is set out in the attached claims.

FIG. 5 shows the detail of a module that is one embodiment of theinvention and the module installed in a cellphone. There is a flexiblebellows (1) sealed onto the end of the module case (9). The bellows (1)is filled with an inert transparent liquid. The bellows is transparentin the centre and, around the transparent region, is metallised to makeelectrical contact with a finger. The metallisation may usemicropyramids or other rough structures to improve the electricalcontact.

One or more photo-emitters (2) transmit light (shown by the dotted line)through the bellows (1). One or more photo-sensors (3) detect the lightscattered back from a finger (15) pressed on the bellows (1).

A pressure sensor (4) measures the pressure in the liquid. a temperaturesensor (5) detects the temperature of any object in its field of view,which is above the module.

the metallisation, photo-emitter(s), photo-sensor(s), pressure sensorand temperature sensor are all connected to a control and interfacingelectronic unit (6). A coble (7) from this unit connects to thecellphone processor using the I2C interface standard. A second cable (8)connects this unit to a pad (12) on the cellphone used to makeelectrical contact to another finger.

The photo-emitter(s), photo-sensor(s), pressure sensor, temperaturesensor and electronic unit may be separate silicon chips or some or allof them may be combined into a single chip.

The module is located at the top of the cellphone casing (12), above thescreen (11). A pad (14) for connection to a finger of the other hand islocated at the bottom of the cellphone case. The user presses his/herindex finger (15) against the bellows (1) to make a measurement. thetemperature sensor is behind a window (16).

FIG. 6 shows the detail of a second module that is another embodiment ofthe invention and the module installed in a cellphone. There is aninextensible strap (21) attached to the module body (29). The surface ofthe strap is metallised to make electrical contact with a finger of auser.

One or more photo-emitters (22) transmits light (shown by the dottedline) beside the strap. One or more photo-sensors (23) detect the lightscattered back from the finger.

There is a slot (24) in the body, below the point at which one end ofthe strap is attached. The beam formed by this slot deforms when forceis applied to the strap and the deformation is measured by a straingauge (25). A proximity sensor (31) measures the distance from the strapto the module body. A temperature sensor (26) detects the temperature ofany object in its field of view, which is above the module.

The metallisation, photo-emitter(s), photo-sensor(s), strain gauge,proximity sensor and temperature sensor are all connected to a controland interfacing electronic unit (30). A cable (27) from this unitconnects to the cellphone processor using the I2C or another interfacestandard. A second cable (28) connects this unit to a pad (34) on thecellphone used to make electrical contact to a finger on the user'sother hand.

The photo-emitter(s), photo-sensor(s), strain gauge temperature sensorand electronic unit may be separate silicon chips or some or all of themmay be combined into a single chip.

The module is located at the top of the cellphone casing (32), above thescreen (33). The pad (34) for connecting to a finger of the other handis located at the bottom of the cellphone case. The user presses hisindex finger (35) against the strap to make a measurement. Thetemperature sensor is behind a window (36).

FIG. 7 shows the detail of a third module that is another embodiment ofthe invention and installation in the cellphone. There is an extensiblestrap (41) that is attaché at one end to the module body (49) and at theother end passes over a roller (45) to a spring (44). Within the spring(not shown) is a sensor to measure its length. The surface of the strapis metalised to make electrical contact with a finger.

One or more photo-emitters (42) transmit light (shown by the dottedline) beside the strap. One or more photo-sensors (43) detect the lightscattered back from the finger.

A proximity sensor (51) measures the distance from the strap to themodule body. A temperature sensor (46) detects the temperature of anyobject in its field of view, which is above the module.

The metallisation, photo-emitter(s), photo-sensor(s), spring lengthsensor, proximity sensor and temperature sensor are all connected to acontrol and interfacing electronic unit (50). a cable (47) from thisunit connects to the cellphone processor using the I2C or anotherinterface standard. A second cable (48) connects this unit to a pad (54)on the cellphone used to make electrical contact to a finger on theuser's other hand.

The photo-emitter(s), photo-sensor(s), proximity sensor, spring lengthsensor, temperature sensor and electronic unit may be separate siliconchips or some or all of them may be combined into a single chip.

The module is located at the top of the cellphone casing (52), above thescreen (53). The pad (54) for connecting to a finger of the other handis located at the bottom of the cellphone casing. The user presseshis/her index finger (55) against the strap to make a measurement. Thetemperature sensor is behind a window (56).

FIG. 8 shows the detail of a fourth module that is another embodiment ofthe invention and installation in the cellphone. there is a plate (61)into which a button (62) is inserted so that the top of the button (62)is flush with the plate. The button (62) rests on a force sensor (63).One or more photo-emitters (64) transmit light (shown by the dottedline) through the top of the button (62). One or more photo-sensors (65)detect the light scattered back from a finger pressed onto the button(62). The top of the button (62) is metallised (not shown).

The metallisation, photo-emitter(s), photo-sensor(s), and force sensorare all connected to a control and interfacing electronic unit (66). Acable (67) from this unit connects to the cellphone processor using theI2C or another interface standard. A second cable (68) connects thisunit to a pad (73) on the cellphone used to make electrical contact to afinger on the user's other hand.

For calibration, the PHHCD may be oriented by the user to be pointingupwards or downwards and the orientation may be detected using thePHHCD's existing sensors. The change in signal of the force sensor underthe weight of the button in these two orientations may be used tocalibrate the force sensor.

A temperature sensor (69) may also be contained within the button (62)or located separately and connected to the button (62). The module islocated at the bottom of the cellphone casing (71), below the screen(72). the pad (73) for connecting to a finger of the other hand islocated at the top of the cellphone casing.

FIG. 9, 10 and 11 show three arrangements of optical sensors to be usedin the PHHM of the present invention to measure the concentration of ananalyte in blood. This may be incorporated into a PHHCD, or may beconnected to a PHHCD, or may be constructed as a stand-alone device withits own user interface, power supply and other electronic and mechanicalcomponents. Not shown is the photoplethysmograph means or the mechanismto modulate the intensity of the light beam. The three illustrationsshow discrete optical and other components; alternatively the sensormight be implemented as one or more integrated optical devices whereseveral optical components are formed in a single blood of transparentplastic.

In FIG. 9, the light source (81) transmits a beam of light that passesthrough a filter (82) to select the spectral band of the light to beused. The spectral band is chosen to allow inexpensive components andmaterials to be used whilst maximising the sensitivity anddiscrimination with respect to the analyte. The beam is collimated by alens (83) to shine through a body part such as finger (84). A beamsplitter (85) divides the beam between a reference cell (86) and samplecell (87). Photosensors (88) measure the intensity of the beam after ithas passed through each cell. A differential amplifier may be used toamplify the difference in signal between the two photosensors.

FIG. 10 shows another implementation in which a sample cell (96)containing gaseous analyte has one or more walls forming a diaphragm(109) moved by an actuator (99).

FIG. 11 shows another implementation in which the light source anddetectors are on the same side of a body part, the detectors beingsensitive to the light scattered back from the body part. A movingmirror (101) reflects light sequentially to each of two fixed mirrors(012) and hence to the reference cell or sample cell. One or morephotosensors (108) measures the intensity of the beam that has passedthe cells.

All of the illustrated embodiments of the PHHM include one or moreelectronic components (not shown) that can include: one or more pressuresensors, one or more analogue to digital convertors, one or moretemperature sensors, a unique identifier and an interface to theelectronic circuits of the cellphone.

1. A personal hand-held monitor (PHHM) comprising a signal acquisitiondevice for acquiring signals which can be used to derive a measurementof a parameter related to the health of the user, the signal acquisitiondevice being integrated with a personal hand-held computing device(PHHCD), where the parameter is blood pressure and the signalacquisition device comprises a blood flow occlusion means adapted to bepressed against one side only of a body part or to have one side only ofa body part pressed against it, a means for measuring the pressureapplied by or to the body part, and a means for detecting the flow ofblood through the body part in contact with the blood flow occlusionmeans.
 2. The personal hand-held monitor of claim 1, wherein the meansfor detecting the flow of blood employs an oscillometric method.
 3. Thepersonal hand-held monitor of claim 1, wherein the means for detectingthe flow of blood is an optical sensor.
 4. The personal hand-heldmonitor of any one of claims 1 to 3, which is adapted to provide audibleor visual instructions to the user to adjust the force with which theblood flow occlusion means is pressed on the body part or with which thebody part is pressed onto the blood flow occlusion means in response tosignals from the PHHM so as to ensure that measurements are made at asufficient range of applied forces to allow the estimation of systolicand diastolic blood pressure.
 5. The personal hand-held monitor of anyof claims 1 to 4, wherein the blood flow occlusion means comprises abutton, the surface of which is adapted to be brought into contact withthe body part, and the means for measuring the pressure includes asensor for determining the force applied to the button.
 6. The personalhand-held monitor of method of claim 5, wherein the force sensor isadapted to be calibrated by orienting the monitor upwards and downwardsand detecting the signal from the force sensor.
 7. The personalhand-held monitor of claim 5 or claim 6, wherein the button comprises aplurality of elements, each of which is connected to a separate forcesensor.
 8. The personal hand-held monitor of any one of claims 1 to 4,wherein the blood occlusion means comprises a pad filled with a fluidand the means for measuring the pressure includes a sensor fordetermining the pressure in the fluid.
 9. The personal hand-held monitorof any one of claims 1 to 4, wherein the blood occlusion means comprisesa strap and the means for measuring the pressure includes a sensor fordetermining the tension in the strap and a sensor for determining thedeflection of the strap.
 10. The personal hand-held monitor of any oneof claims 1 to 9, wherein the processor of the PHHM is adapted toestimate systolic and diastolic blood pressure by fitting the measureddata to a theoretical curve that relates blood flow rate to externalapplied pressure.
 11. A personal hand-held monitor comprising a signalacquisition device for acquiring signals which can be used to derive ameasurement of a parameter related to the health of the user, the signalacquisition device being integrated with a personal hand-held computingdevice, wherein the parameter is blood pressure and the signalacquisition device comprises a blood flow occlusion means adapted toocclude flow of blood through a body part, means for detecting the flowof blood through the body part in contact with the blood flow occlusionmans and at least one other means providing a signal from which anestimate of the user's blood pressure can be derived, wherein theprocessor of the PHHM is adapted to process the signals from said atleast two means according to a mathematical algorithm to derive a moreaccurate estimate of the blood pressure of the user.
 12. The personalhand-held monitor of claim 11, wherein the other means for providingsignals from which an estimate of the user's blood pressure can bederived is selected from a blood pressure sensor; a means for estimatingPulse Wave Velocity; a means for estimating pulse volume; and a meansfor estimating pulse rate.
 13. The personal hand-held monitor of claim12 which includes all four means.
 14. The personal hand-held monitor ofclaim 11 or claim 12, wherein the means for estimating Pulse WaveVelocity is adapted to determine the time delay between the electricalsignal which initiates systole and the mechanical initiation of systole.15. The personal hand-held monitor of claim 11 or claim 12, wherein themeans for estimating Pulse Wave Velocity receives a signal indicative ofthe electrical signal which initiates systole and signals indicative ofthe arrival of a pulse at two different locations on the body of theuser.
 16. The personal hand-held monitor of any one of claims 12 to 15,wherein the means for estimating Pulse Wave Velocity receives signalsindicative of the user's personal data, such as the user's sex, age,weight, height, waist circumference or other physical characteristics,whereby the accuracy of the blood pressure estimate may be increased.17. The personal hand-held monitor of any one of claims 12 to 16,wherein the processor of the PHHM is adapted to analyse the variationsin the interval between successive pulses.
 18. The personal hand-heldmonitor of any one of claims 12 to 16, wherein the processor of the PHHMis adapted to estimate the user's blood pressure at another part of thebody, such as the upper arm or in the aorta, from the measured value.19. The personal hand-held monitor of any one of claims 1 to 18, whichis adapted to receive signals indicative of an independent calibrationmeasurement of the user's blood pressure, whereby the accuracy of theblood pressure estimate may be increased.
 20. A personal hand-heldmonitor comprising a signal acquisition device for acquiring signalswhich can be used to derive a measurement of a parameter related to thehealth of the user, the signal acquisition device being integrated witha personal hand-held computing device, wherein the signal acquisitiondevice comprises a temperature sensor adapted to measure the temperatureof a body part while the body part is covered by the monitor and whereinthe processor of the PHHM is adapted to process changes in the signalfrom the temperature sensor according to a mathematical algorithm toderive a measurement of the user's core body temperature.
 21. A personalhand-held monitor comprising a signal acquisition device for acquiringsignals which can be used to derive a measurement of a parameter relatedto the health of the user, the signal acquisition device beingintegrated with a personal hand-held computing device, wherein thesignal acquisition device comprises a temperature sensor adapted tomeasure the temperature of a body part at which the monitor is directedand wherein the processor of the PHHM is adapted to process changes inthe signal from the temperature sensor according to a mathematicalalgorithm to derive a measurement of the user's core body temperature.22. The personal hand-held monitor of claim 21, wherein the PHHM isadapted to provide audible and/or visual instructions to the user toposition the sensor to obtain the most relevant measurement.
 23. Thepersonal hand-held monitor of claim 21 or claim 22, wherein the PHHM isadapted to provide audible and/or visual instructions to the user toposition the sensor so that it is directed at the user's clothing,whereby a signal related to ambient temperature can be obtained.
 24. Thepersonal hand-held monitor of any one of claims 20 to 23, wherein thetemperature sensor is collocated or combined with a loudspeaker or otherdevice used to generate sound in the PHHCD.
 25. A personal hand-heldmonitor comprising a signal acquisition device for acquiring signalswhich can be used to derive a measurement of a parameter related to thehealth of the user, the signal acquisition device being integrated witha personal hand-held computing device, wherein the signal acquisitiondevice comprises a blood photosensor having a photoemitter fortransmitting light to a body part of a user, a photodetector fordetecting light transmitted through or scattered by the body part and anoptical cell, containing the analyte to be detected, through which lighttransmitted through or scattered by the body part passes before itreaches the photodetector, wherein the processor of the PHHM is adaptedto process signals obtained from the phodetector in the presence of thebody part and in the absence of the body part to provide a measurementof the concentration of the analyte in the user's blood.
 26. Thepersonal hand-held monitor of claim 25, wherein the PHHM is adapted tomake measurements at one or more times during the cycle of the pulse inthe body part, including at least one measurement made at or near thepeak of the systole.
 27. The personal hand-held monitor of claim 25 orclaim 26, wherein the analyte is glucose, ethanol, haemoglobin,creatinine or cholesterol.
 28. the personal hand-held monitor of claim25 or claim 26, wherein the analyte is an illegal or otherwise forbiddendrug or stimulant.
 29. The personal hand-held monitor of any one ofclaims 25 to 28, wherein the optical system is integrated.
 30. A signalacquisition device as defined in any one of claims 25 to 29, which isequipped with a stand-alone display, controls, computing device andelectrical power supply.
 31. The PHHM according to any one of claims 1to 29, wherein the PHHCD is a cellphone or a tablet computer.
 32. ThePHHM according to claim 31, wherein the PHHCD is adapted to be connectedvia a network to a data processing system for analysing the data fromthe PHHM to extract health-related parameters or more accuratehealth-related parameters than are available from the PHHCD alone andfor returning the results of the analysis to the PHHCD for display tothe user.
 33. The PHHM according to claim 31 or claim 32, wherein thePHHCD is adapted to be connected via a network to a data processingsystem for retaining copies of data for subsequent review by the user orby other persons, such as medical practitioners.
 34. The PHHCD accordingto claim 33, wherein the data processing system is adapted to controlaccess by third party applications to the data from the PHHM so as topermit such access only for applications which satisfy regulatoryrequirements and/or for which a licence has been granted by the dataprocessing system.
 35. A signal acquisition device adapted to beintegrated with a PHHCD to produce a PHHM as defined in any one ofclaims 1 to 34.